The purpose of the proposed study is to determine the extent to which electrical potentials can influence osteogenic activity in porous implant materials. The growth of tissue into porous implants has been well established as a feasible means of attaching load-bearing prosthesis to the musculo-skeletal system. Attachment by ingrowth eliminates most of the problems associated with other means of fixation but has itself the disadvantage that the patient must be immobilized for long periods to permit sufficient ingrowth to ensure stability. The stimulation of bone by imposed electrical potentials has been demonstrated for fracture healing and for some 'preliminary' bone growth into porous implants. The proposed study is directed to broaden our knowledge of the effect of electrical stimulation on (1) the actual interfacial strength of implant/tissue union (2) the kinetics of tissue ingrowth (3) the morphology of the union. Carefully machined tensile specimens will be made to test the strength of the unions and comparisons will be made between the electrically stimulated and non-stimulated control samples. The kinetics of tissue ingrowth will be determined quantitatively by a combination of wet chemical assaying and microscopic techniques. A porous ceramic (aluminum oxide), polymer (polymethylmethacrylate) and metal (Co-Cr-Mo alloy) with a pore size of approximately 100 micron m diameter or larger will be used since these materials were previously studied for their usefulness as porous implant materials in orthopedic and dental application.